In this mentored clinical scientist training proposal, the applicant will test the hypothesis that probiotic and commensal bacterial organisms secrete soluble, heat-labile proteins exert their beneficial effects by the induction of cytoprotective heat shock proteins (hsp) and the inhibition of the proinflammatory NF-kappaB pathway in gut epithelial cells. Preliminary data strongly support this hypothesis and show feasibility of proposed approaches. Studies are aimed at examining specific mechanisms of probiotic action, the relative roles of the aforementioned actions in mediating probiotic action, and identifying bioactive probiotic proteins. These investigations will provide an outstanding training opportunity for the applicant to learn how to examine transcriptional and post-transcriptional processes, learn epithelial biology, and acquire additional skills in molecular and cell biology, including imaging technology. Finally, the applicant will learn biochemical techniques to identify and purify the active components of the bacterial conditioned media. The applicant, Elaine O. Petrof, MD, M.Sc., completed her Infectious Diseases fellowship and went on to pursue a Clinical Pharmacology fellowship at the University of Chicago. During this period, she entered the IBD laboratory of Dr. Eugene Chang to seek additional basic science training and to study the effect of probiotics and commensal flora on gut epithelium. The proposed training plan provides 75% protected time, numerous opportunities to acquire new skills and experience in cell and molecular biology, didactic training in techniques and proper conduct in research, meaningful interactions with other experienced investigators, and phased transition steps for the applicant to mature as an independent investigator. The applicant's research will form a solid foundation for future research required to develop a career in academic medicine